count（a.selected_he =“yes”）是否可以？

Question

我能问这样的：

having count(a.selected_he = "yes") > 2 

我想问如果结果的计数记录了selected_he = yes超过2。 但我不确定我可以在计数功能中写入a.selected_he = "yes"。

我对不对？

Answer 1

SELECT sum(CASE WHEN a.selected_he='yes' THEN 1 ELSE 0 END)>2 FROM ... 

count计数非null S，不true秒。

Answer 2

select id,count(*) as counts 
from table 
where selected_he = 'yes' 
group by id 
having counts > 2 

如果where子句中的列不包含空值。